I want to use the new customDump and diff features in my reducer. Do I replace .debug()?

Mozahler · 2021-08-25T18:31:24.823Z

Loving the newest releases, and am eager to do something new with the customDump command in the swift-custom-dump package.
A good use out of the box would be to call it at the end of the reducer (where I now have a call to debug()). When I update a record in an array I'm getting a diff that includes all the unaltered objects as well as the changed ones, and I'd prefer something similar to the print(diff(a, b)) where a is the previous call to the reducer and b is the current. and I'd see something like ... (4 unchanged) instead of the member objects listed with all their unchanged details. Where do I start?

mbrandonw · 2021-08-25T18:35:41.304Z

Hi @Mozahler, what you are describing should already be the default behavior if you are running the newest version of TCA in your code base.

For example, if I open the repo's workspace, run the Todos application, and add a bunch of todos, I see the following printed to the console when I complete a todo:

received action:
  AppAction.todo(
    id: UUID(FED4EAE4-F029-47D0-9FBB-5A58372629A1),
    action: TodoAction.checkBoxToggled
  )
  AppState(
    editMode: EditMode.inactive,
    filter: Filter.all,
    todos: [
      … (4 unchanged),
      [4]: Todo(
        description: "",
        id: UUID(FED4EAE4-F029-47D0-9FBB-5A58372629A1),
-       isComplete: false
+       isComplete: true
      ),
      … (5 unchanged)
    ]
  )

If you are not seeing this behavior then you may need to update your packages to use the newest release of TCA.

Mozahler · 2021-08-25T18:36:28.806Z

I'm using 0.25.1. OK. I'm seeing it in the output now. I need to determine why it's still more verbose than I expect. Thanks for the quick response!

mbrandonw · 2021-08-25T18:39:04.703Z

Can you share some output logs you are seeing from using .debug()?

Mozahler · 2021-08-25T18:45:57.170Z

Here's the output from a REST query to Stack Overflow. I don't think there's anything wrong with it. It's just a lot to wade through.
"""

received action:
  SimplySoAction.processQuestionQueryResult(
    Result.success(
      [
        [0]: Question(
          id: 68864217,
          score: 3,
          title: "SwiftUI - Calculate height for long GeometryReader inside ScrollView",
          body: nil,
          tags: [
            [0]: "ios",
            [1]: "swiftui",
            [2]: "geometryreader",
            [3]: "swiftui-scrollview"
          ],
          owner: User(
            aboutMe: nil,
            acceptRate: 83,
            accountId: 2236007,
            answerCount: nil,
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            questionCount: nil,
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            userId: 1972372,
            viewCount: nil
          ),
          answerCount: 2,
          viewCount: 93,
          acceptedAnswerId: nil,
          date: Date(2021-08-20T14:57:07.000Z)
        ),
        [1]: Question(
          id: 68878275,
          score: 2,
          title: "How to apply a dynamic rotation to a map using SwiftUI",
          body: nil,
          tags: [
            [0]: "swift",
            [1]: "swiftui",
            [2]: "rotation",
            [3]: "mapbox",
            [4]: "safearea"
          ],
          owner: User(
            aboutMe: nil,
            acceptRate: nil,
            accountId: 21095035,
            answerCount: nil,
            badgeCounts: nil,
            creationDate: nil,
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            profileImage: URL(https://www.gravatar.com/avatar/8bdb1ef6b5a6fe52f4acaad280472507?s=128&d=identicon&r=PG&f=1),
            questionCount: nil,
            reputation: 133,
            userId: 15506187,
            viewCount: nil
          ),
          answerCount: 1,
          viewCount: 53,
          acceptedAnswerId: nil,
          date: Date(2021-08-22T03:27:58.000Z)
        ),
        [2]: Question(
          id: 68900888,
          score: 2,
          title: "How do I properly perform Dependency Injection into SwiftUI StateObjects?",
          body: nil,
          tags: [
            [0]: "ios",
            [1]: "swift",
            [2]: "dependency-injection",
            [3]: "swiftui"
          ],
          owner: User(
            aboutMe: nil,
            acceptRate: nil,
            accountId: 6989074,
            answerCount: nil,
            badgeCounts: nil,
            creationDate: nil,
            displayName: "Mai Anh Vu",
            lastAccessDate: nil,
            lastModifiedDate: nil,
            profileImage: URL(https://www.gravatar.com/avatar/5c15a1f87f1e7150ee9f9100d1f37c65?s=128&d=identicon&r=PG),
            questionCount: nil,
            reputation: 29,
            userId: 5358977,
            viewCount: nil
          ),
          answerCount: 0,
          viewCount: 35,
          acceptedAnswerId: nil,
          date: Date(2021-08-24T01:54:25.000Z)
        )
      ]
    )
  )
  SimplySoState(
    questions: [
+     [0]: Question(
+       id: 68864217,
+       score: 3,
+       title: "SwiftUI - Calculate height for long GeometryReader inside ScrollView",
+       body: nil,
+       tags: [
+         [0]: "ios",
+         [1]: "swiftui",
+         [2]: "geometryreader",
+         [3]: "swiftui-scrollview"
+       ],
+       owner: User(
+         aboutMe: nil,
+         acceptRate: 83,
+         accountId: 2236007,
+         answerCount: nil,
+         badgeCounts: nil,
+         creationDate: nil,
+         displayName: "Big_Chair",
+         lastAccessDate: nil,
+         lastModifiedDate: nil,
+         profileImage: URL(https://i.stack.imgur.com/h3gwk.jpg?s=128&g=1),
+         questionCount: nil,
+         reputation: 912,
+         userId: 1972372,
+         viewCount: nil
+       ),
+       answerCount: 2,
+       viewCount: 93,
+       acceptedAnswerId: nil,
+       date: Date(2021-08-20T14:57:07.000Z)
+     ),
+     [1]: Question(
+       id: 68878275,
+       score: 2,
+       title: "How to apply a dynamic rotation to a map using SwiftUI",
+       body: nil,
+       tags: [
+         [0]: "swift",
+         [1]: "swiftui",
+         [2]: "rotation",
+         [3]: "mapbox",
+         [4]: "safearea"
+       ],
+       owner: User(
+         aboutMe: nil,
+         acceptRate: nil,
+         accountId: 21095035,
+         answerCount: nil,
+         badgeCounts: nil,
+         creationDate: nil,
+         displayName: "nickcoding2",
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+         lastModifiedDate: nil,
+         profileImage: URL(https://www.gravatar.com/avatar/8bdb1ef6b5a6fe52f4acaad280472507?s=128&d=identicon&r=PG&f=1),
+         questionCount: nil,
+         reputation: 133,
+         userId: 15506187,
+         viewCount: nil
+       ),
+       answerCount: 1,
+       viewCount: 53,
+       acceptedAnswerId: nil,
+       date: Date(2021-08-22T03:27:58.000Z)
+     ),
+     [2]: Question(
+       id: 68900888,
+       score: 2,
+       title: "How do I properly perform Dependency Injection into SwiftUI StateObjects?",
+       body: nil,
+       tags: [
+         [0]: "ios",
+         [1]: "swift",
+         [2]: "dependency-injection",
+         [3]: "swiftui"
+       ],
+       owner: User(
+         aboutMe: nil,
+         acceptRate: nil,
+         accountId: 6989074,
+         answerCount: nil,
+         badgeCounts: nil,
+         creationDate: nil,
+         displayName: "Mai Anh Vu",
+         lastAccessDate: nil,
+         lastModifiedDate: nil,
+         profileImage: URL(https://www.gravatar.com/avatar/5c15a1f87f1e7150ee9f9100d1f37c65?s=128&d=identicon&r=PG),
+         questionCount: nil,
+         reputation: 29,
+         userId: 5358977,
+         viewCount: nil
+       ),
+       answerCount: 0,
+       viewCount: 35,
+       acceptedAnswerId: nil,
+       date: Date(2021-08-24T01:54:25.000Z)
+     )
    ],
    currentTab: TabValues.Asked,
    userInfo: User(…),
    userInfoSheet: UserSheet(…),
    answers: Set([]),
    isLoading: false,
    isConnected: true,
    badgeCount: 0
  )

received action:
  SimplySoAction.handleUserInfo(
    Result.success(
      [
        [0]: User(
          aboutMe: nil,
          acceptRate: 82,
          accountId: 6683987,
          answerCount: nil,
          badgeCounts: BadgeCount(
            bronze: 42,
            silver: 25,
            gold: 6
          ),
          creationDate: Date(2015-07-25T18:57:36.000Z),
          displayName: "Mozahler",
          lastAccessDate: Date(2021-08-25T17:29:46.000Z),
          lastModifiedDate: Date(2021-06-01T19:05:00.000Z),
          profileImage: URL(https://i.stack.imgur.com/AXyaZ.jpg?s=128&g=1),
          questionCount: nil,
          reputation: 3831,
          userId: 5156054,
          viewCount: nil
        )
      ]
    )
  )
  SimplySoState(
    questions: […],
    currentTab: TabValues.Asked,
    userInfo: User(…),
    userInfoSheet: UserSheet(
-     id: UUID(1B5F81DD-3D18-4A7D-AC78-859EB92A7262),
+     id: UUID(26166E08-AEC6-4211-9FD7-BC4B11CED53F),
      user: User(…)
    ),
    answers: Set([]),
    isLoading: false,
    isConnected: true,
    badgeCount: 0
  )

received action:
  SimplySoAction.processQuestionQueryResult(
    Result.success(
      [
        [0]: Question(
          id: 68864217,
          score: 3,
          title: "SwiftUI - Calculate height for long GeometryReader inside ScrollView",
          body: nil,
          tags: [
            [0]: "ios",
            [1]: "swiftui",
            [2]: "geometryreader",
            [3]: "swiftui-scrollview"
          ],
          owner: User(
            aboutMe: nil,
            acceptRate: 83,
            accountId: 2236007,
            answerCount: nil,
            badgeCounts: nil,
            creationDate: nil,
            displayName: "Big_Chair",
            lastAccessDate: nil,
            lastModifiedDate: nil,
            profileImage: URL(https://i.stack.imgur.com/h3gwk.jpg?s=128&g=1),
            questionCount: nil,
            reputation: 912,
            userId: 1972372,
            viewCount: nil
          ),
          answerCount: 2,
          viewCount: 93,
          acceptedAnswerId: nil,
          date: Date(2021-08-20T14:57:07.000Z)
        ),
        [1]: Question(
          id: 68878275,
          score: 2,
          title: "How to apply a dynamic rotation to a map using SwiftUI",
          body: nil,
          tags: [
            [0]: "swift",
            [1]: "swiftui",
            [2]: "rotation",
            [3]: "mapbox",
            [4]: "safearea"
          ],
          owner: User(
            aboutMe: nil,
            acceptRate: nil,
            accountId: 21095035,
            answerCount: nil,
            badgeCounts: nil,
            creationDate: nil,
            displayName: "nickcoding2",
            lastAccessDate: nil,
            lastModifiedDate: nil,
            profileImage: URL(https://www.gravatar.com/avatar/8bdb1ef6b5a6fe52f4acaad280472507?s=128&d=identicon&r=PG&f=1),
            questionCount: nil,
            reputation: 133,
            userId: 15506187,
            viewCount: nil
          ),
          answerCount: 1,
          viewCount: 53,
          acceptedAnswerId: nil,
          date: Date(2021-08-22T03:27:58.000Z)
        ),
        [2]: Question(
          id: 68900888,
          score: 2,
          title: "How do I properly perform Dependency Injection into SwiftUI StateObjects?",
          body: nil,
          tags: [
            [0]: "ios",
            [1]: "swift",
            [2]: "dependency-injection",
            [3]: "swiftui"
          ],
          owner: User(
            aboutMe: nil,
            acceptRate: nil,
            accountId: 6989074,
            answerCount: nil,
            badgeCounts: nil,
            creationDate: nil,
            displayName: "Mai Anh Vu",
            lastAccessDate: nil,
            lastModifiedDate: nil,
            profileImage: URL(https://www.gravatar.com/avatar/5c15a1f87f1e7150ee9f9100d1f37c65?s=128&d=identicon&r=PG),
            questionCount: nil,
            reputation: 29,
            userId: 5358977,
            viewCount: nil
          ),
          answerCount: 0,
          viewCount: 35,
          acceptedAnswerId: nil,
          date: Date(2021-08-24T01:54:25.000Z)
        )
      ]
    )
  )
  (No state changes)

"""

mbrandonw · 2021-08-25T19:01:40.527Z

Ah I see. Everything being printed is the data inside the action. That data can't be diff'd because there's no before and after. It's just data coming in from the outside world.

If you want to omit the data from the action to make things easier to read you can provide the argument actionFormat: .labelsOnly to the .debug() method:

github.com

pointfreeco/swift-composable-architecture/blob/1f2f6124be52d094b20ed510de9c6fdf5a977fcf/Sources/ComposableArchitecture/Debugging/ReducerDebugging.swift#L45


      
          ///
          /// - Parameters:
          ///   - prefix: A string with which to prefix all debug messages.
          ///   - toDebugEnvironment: A function that transforms an environment into a debug environment by
          ///     describing a print function and a queue to print from. Defaults to a function that ignores
          ///     the environment and returns a default ``DebugEnvironment`` that uses Swift's `print`
          ///     function and a background queue.
          /// - Returns: A reducer that prints debug messages for all received actions.
          public func debug(
            _ prefix: String = "",
            actionFormat: ActionFormat = .prettyPrint,
            environment toDebugEnvironment: @escaping (Environment) -> DebugEnvironment = { _ in
              DebugEnvironment()
            }
          ) -> Reducer {
            self.debug(
              prefix,
              state: { $0 },
              action: .self,
              actionFormat: actionFormat,
              environment: toDebugEnvironment

Mozahler · 2021-08-25T19:04:59.033Z

Thank you. Of course there's a parameter. Next time I'll look first. Appreciate your help!

mayoff · 2021-08-25T23:08:25.801Z

You can also use a CasePath to focus on just some actions, or just part of some actions, using the action argument of the four-argument debug operator. By constructing a custom CasePath<Action, Any>, you can be very specific about what parts of each action you print.

github.com

pointfreeco/swift-composable-architecture/blob/3c51885b983b623f0cc506660d79b02d45a8ffc1/Sources/ComposableArchitecture/Debugging/ReducerDebugging.swift#L102


      
          ///   - toLocalState: A function that filters state to be printed.
          ///   - toLocalAction: A case path that filters actions that are printed.
          ///   - toDebugEnvironment: A function that transforms an environment into a debug environment by
          ///     describing a print function and a queue to print from. Defaults to a function that ignores
          ///     the environment and returns a default ``DebugEnvironment`` that uses Swift's `print`
          ///     function and a background queue.
          /// - Returns: A reducer that prints debug messages for all received actions.
          public func debug<LocalState, LocalAction>(
            _ prefix: String = "",
            state toLocalState: @escaping (State) -> LocalState,
            action toLocalAction: CasePath<Action, LocalAction>,
            actionFormat: ActionFormat = .prettyPrint,
            environment toDebugEnvironment: @escaping (Environment) -> DebugEnvironment = { _ in
              DebugEnvironment()
            }
          ) -> Reducer {
            #if DEBUG
              return .init { state, action, environment in
                let previousState = toLocalState(state)
                let effects = self.run(&state, action, environment)
                guard let localAction = toLocalAction.extract(from: action) else { return effects }

Mozahler · 2021-08-27T14:57:10.390Z

Thank you, Rob. Definitely food for thought. Time to ruminate.